Well I assume you have a way to share files (e.g. Your NAS that you can use to share your media files)
You then can use ssh to copy the file. Alternatively you could use scp to copy the file.
Details regarding how to access the command line interface can be found here on our Wiki: Accessing the command line - General - OSMC
Here is a cheatsheet and some tutorials for how to navigate in a Linux shell: Cheatsheets and Tutorials for users new to Linux based operating systems